And yet another item on the iPad? Are we serious? Yes, we are, since this one is about something that even geeks who aren't interested in the iPad itself should find intriguing. Steve Jobs said yesterday that the iPad is powered by an Apple A4 processor, but contrary to what many seem to think - it wasn't designed in-house at all.

By "universal" binaries, they actually only mean PPC and X86 binaries, not ARM. They aren't really "universal" at all.

They also mean only binaries from Apple, as I'm pretty sure that only Apple bothered with it. Possibly even less "universal" than at first glance.

Huh?

Apple has shipped Mac OS X computers using various PPC and Intel chips. They have not yet shipped one running on ARM. Why would their universal binaries contain ARM executables?

It's not just Apple that ships universal binaries. Virtually every Mac OS X application shipped in the past few years has been a universal binary - even before the Intel transition a binary would typically contain multiple executables each optimised for different types of PPC processor. As a developer XCode essentially handles all this for you, making it harder to not build universal binaries.

Should Apple decide to ship ARM-based Macs creating native apps would mostly just be a case of rebuilding them (so you'd end up with an ARM executable in addition to the existing ones). The toolchain already supports this. Of course should this happen Apple would most likely also include a Rosetta layer to let those ARM-based Macs run existing Intel/PPC Mac binaries as they did with the PPC to Intel transition.

"By "universal" binaries, they actually only mean PPC and X86 binaries, not ARM. They aren't really "universal" at all.

They also mean only binaries from Apple, as I'm pretty sure that only Apple bothered with it. Possibly even less "universal" than at first glance.

Huh?

Apple has shipped Mac OS X computers using various PPC and Intel chips. They have not yet shipped one running on ARM. Why would their universal binaries contain ARM executables? "

That is exactly the point ... Apple's "universal" binaries support, as you say, only "Mac OS X computers using various PPC and Intel chips". Therefore, Apples so-called "universal" binaries won't actually support ARM.

The Apple iPad uses an ARM CPU.

So ... no OSX applications for the iPad. The iPad is just a big smartphone that isn't even a phone.

It's not just Apple that ships universal binaries. Virtually every Mac OS X application shipped in the past few years has been a universal binary - even before the Intel transition a binary would typically contain multiple executables each optimised for different types of PPC processor. As a developer XCode essentially handles all this for you, making it harder to not build universal binaries.

Should Apple decide to ship ARM-based Macs creating native apps would mostly just be a case of rebuilding them (so you'd end up with an ARM executable in addition to the existing ones). The toolchain already supports this. Of course should this happen Apple would most likely also include a Rosetta layer to let those ARM-based Macs run existing Intel/PPC Mac binaries as they did with the PPC to Intel transition.

Huh?

Who said anything about "ARM-based Macs"? This thread is about the iPad.

Just because a binary doesn't include a specific arch doesn't mean it's not a UB (yes I know that sounds weird but keep reading) .

Apple *DO* create ARM code 'universal binaries' - UB's are merely a container for various different architecture code - It's what the Magic Bit is for at the start of ALL binaries compiled by Xcode).

Also every single iphone application can be compiled to run on the iPhone simulator. The key thing to know is that the iphone simulator is exactly what it says it is - it is a simulator which runs x86 code not ARM - it is NOT an emulator.

It's also highly likely there is a full OSX Snow Leopard build running on Arm deep in the bowels of Apple just as there were builds on 10.0 running on x86 for years before his Jobsness admitted it during a keynote.